The present invention relates to devices used to control the flow of fluid through vehicle fluid systems, such as a vehicle anti-lock brake system.
For safety concerns, many of today""s vehicles are equipped with anti-lock brake systems (ABS). An ABS maintains vehicle control during extreme braking by electronically sensing when the wheels are just about to lock up and releasing the brakes before lock up occurs. An ABS is capable of modulating the pressure in the wheel cylinders in order to keep the wheels from slipping on the roadway during harsh braking conditions.
In general, a typical anti-lock brake system can include several solenoid valves to control the hydraulic fluid pressure in the individual components, e.g., a master cylinder, and a plurality of wheel cylinders. Usually a normally open solenoid valve is installed between the master cylinder and each wheel cylinder. During normal braking these valves permit uninhibited fluid communication between the master cylinder and the wheel cylinder. However, in the event of panic brake application by a driver, these valves are energized to provide a smooth and stable cycling of fluid pressure to the wheel cylinders in order to prevent brake lock-up. A very common solenoid valve used in the above described application includes a relatively small chromium steel ball that is crimped into the nose of a valve poppet. When the valve is energized, the steel ball engages a chamfered valve seat in order to block fluid communication through the valve. Unfortunately, it happens that the crimp holding the steel ball within the nose of the poppet can fail and cause the steel ball to fall out of the nose of the poppet and damage the valve, the master cylinder, or the wheel cylinder. Moreover, if it is necessary to decrease the size of the ball so that it will fit into a relatively small valve seat, the process to crimp the nose of the poppet around the steel ball becomes increasingly difficult. Thus, the minimum size of the ball, the corresponding valve seat and the inlet orifice is limited by the crimping process and flow restrictions through the inlet port. It also happens that the crimped material around the steel ball can restrict flow around the nose of the poppet when the valve is open.
The present invention has recognized the above-mentioned prior art drawbacks, and has provided the below-disclosed solutions to one or more of the prior art deficiencies.
A vehicle solenoid valve includes an inlet port that is circumscribed by a rounded, cup-shaped valve seat and an outlet port. Within the valve, is a poppet that has a rounded nose which is configured to engage the valve seat. The poppet is movable between an open configuration, wherein the rounded nose is distanced from the valve seat, and a closed configuration, wherein the rounded nose engages the valve seat to block fluid communication through the valve.
In a preferred embodiment, the poppet includes a non-magnetic poppet shaft and a poppet head that is attached to the shaft. Preferably, the poppet head includes a frustum-shaped portion that is contiguous to the nose and a cylindrical portion that is contiguous to the frustum-shaped portion. In a preferred embodiment, the valve communicates with a wheel brake cylinder and a master brake cylinder to selectively control fluid communication therebetween.
In another aspect of the present invention, a solenoid valve poppet includes a non-magnetic poppet shaft and a poppet head that is connected to the poppet shaft. In this aspect of the present invention, the poppet head has a rounded nose.
In yet another aspect of the present invention, a valve for selectively establishing communication between a vehicle master brake cylinder and a vehicle wheel brake cylinder includes an inlet port and an outlet port. The inlet port is connected to one of: the master brake cylinder and the wheel brake cylinder and the outlet port is connected to the other. In this aspect of the present invention, one of the ports forms a valve seat and the valve includes a multi-piece poppet that has a frustum-shaped poppet head that terminates in a nose which is configured for engaging the valve seat.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: